ORIGINAL PAPER Distribution of detritivores in tropical forest streams of peninsular Malaysia: role of temperature, canopy cover and altitude variability Md Rawi Che Salmah & Salman Abdo Al-Shami & Ahmad Abu Hassan & Madziatul Rosemahanie Madrus & Abdul Nurul Huda Received: 4 May 2012 / Revised: 2 February 2013 / Accepted: 3 February 2013 # ISB 2013 Abstract The diversity and abundance of macroinvertebrate shredders were investigated in 52 forested streams (local scale) from nine catchments (regional scale) covering a large area of peninsular Malaysia. A total of 10,642 individuals of aquatic macroinvertebrates were collected, of which 18.22 % were shredders. Biodiversity of shredders was described by alpha (α average ), beta (β) and gamma diversity (γ) measures. We found high diversity and abundance of shredders in all catchments, represented by 1,939 individuals (range 6–115 and average per site of 37.29±3.48 SE) from 31 taxa with 2–13 taxa per site (α average =6.98±0.33 SE) and 10–15 taxa per catchment (γ =13.33±0.55 SE). At the local scale, water temperature, stream width, depth and altitude were correlated significantly with diversity (Adj-R 2 =0.205). Meanwhile, dissolved oxygen, stream velocity, water temperature, stream width and altitude were correlated to shredder abundance (Adj-R 2 =0.242). At regional scale, however, water tempera- ture was correlated negatively with β and γ diversity (r 2 = 0.161 and 0.237, respectively) as well as abundance of shred- ders (r 2 =0.235). Canopy cover was correlated positively with β diversity (r 2 =0.378) and abundance (r 2 =0.266), mean- while altitude was correlated positively with β (quadratic: r 2 =0.175), γ diversity (quadratic: r 2 =0.848) as well as abundance (quadratic: r 2 =0.299). The present study is considered as the first report describing the biodiversity and abundance of shredders in forested headwater streams across a large spatial scale in peninsular Malaysia. We con- cluded that water temperature has a negative effect while altitude showed a positive relationship with diversity and abundance of shredders. However, it was difficult to detect an influence of canopy cover on shredder diversity. Keywords Shredders . Peninsular Malaysia . Altitude . Canopy cover . Temperature Introduction Tropical forests, including those in South East (SE) Asia, are known to be hotspots for global biodiversity (Sodhi and Brook 2006; Boyero et al. 2009). The loss of these habitats may have adverse effect on global extinction rates (Douglas et al. 1992; Sodhi and Brook 2006) and on the ability of these forests to provide essential ecosystem services to humans (Hector et al. 2011). Forest headwater streams are major elements of river networks as they can contribute more than three-quarters of stream channel length in any drainage basin (Clarke et al. 2008). Despite their small catchment size, forest headwater streams are unique ecosystems as their biology and ecology are vastly influenced by the surrounding riparian vegetation cover (for review, see Clarke et al. 2008). The fallen leaf litter sustains continuous allochthonous material for aquatic invertebrates. The decomposition of the leaf litter in head- water streams involves mechanical, chemical and microbial processes (Webster and Benfield 1986). Consequently, headwater streams are essential spots for organic matter processing (Wallace et al. 1997; Clarke et al. 2008) and for nutrient cycling (Bernhardt et al. 2005). Electronic supplementary material The online version of this article (doi:10.1007/s00484-013-0648-9) contains supplementary material, which is available to authorized users. M. R. Che Salmah : S. A. Al-Shami (*) : A. Abu Hassan : M. R. Madrus : A. Nurul Huda School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia e-mail: salshami@usm.my S. A. Al-Shami e-mail: alshami200@gmail.com Int J Biometeorol DOI 10.1007/s00484-013-0648-9